A primary health concern for aging adults is balance deterioration, which severely limits their activities of daily living and community participation. While a decline in the ability to use compensatory (feedback) mechanisms of postural control have been studied in this population, the utilization of anticipatory (feed forward) postural adjustments in the elderly is not well documented. Inability of older adults to optimally generate postural adjustments prior to (in anticipation of) an upcoming balance threat may put them at a greater risk for losing balance. Understanding the effect of aging on the utilization of anticipatory postural adjustments in subsequent control of posture requires studying the two mechanisms together. Recently, the PIs developed a new method of applying external body perturbations that allows them to examine the individual effects of each mechanism of postural control and their interaction. Given the insufficiency of data on the anticipatory postural control in the elderly and the availability of a novel experimental technique, the objectives of this study are: 1) to provide important baseline information regarding the generation of anticipatory postural adjustments in older individuals, 2) to investigate the interaction between anticipatory and compensatory mechanisms of balance control in older adults, and 3) to examine the effect of differences in functional balance capacity of older adults on the interaction between anticipatory and compensatory mechanisms of balance control. Two specific aims will be tested in experiments involving older (functionally stable and unstable) and young adults subjected to external perturbations while standing. Electromyographic recordings, ground reaction forces, and kinematic data will be collected and analyzed. Current rehabilitation strategies in the elderly are not focused on restoration of feed forward postural control, mainly due to an inadequate understanding of the role of anticipatory postural adjustments in balance control. This study will form the foundation for a longer-term research program centered on retraining the ability of older adults to use anticipatory adjustments in maintenance and improvement of balance control. PUBLIC HEALTH RELEVANCE: The proposed project will study control of posture in the elderly. The PIs will investigate the differences in utilization of anticipatory postural adjustments between older (functionally stable and unstable) and young adults subjected to external perturbations while standing. The outcome of the study is important for the future development of therapeutic advances focused on treatment of postural disorders.